You've completed your estate plan. That's a tremendous accomplishment -- and one that too many people never get around to. You've got some peace of mind.
Your attorney likely is keeping the original documents (in paper as well as electronic versions). They probably presented you with an impressive binder containing copies of everything. It may look like something you should put on your bookshelf -- but it isn't.
It's essential to keep these documents in a safe place, yet one that's accessible to those who will need to have them when the time comes. A fireproof home safe or file cabinet is probably the best option.
For many people, their safe deposit box at the local bank is their go-to storage place for important documents and valuables. However, this isn't a good place for any documents that your executor or loved ones will need if you pass away or become incapacitated. Even if you give them a key, they won't be allowed access to the box without the appropriate legal authority.
You may, however, wish to place extra copies of some of your estate planning documents in your safe deposit box. You should also have an electronic version of your estate plan where your executor and/or others who will be managing your affairs or estate can access it but where it is protected from unauthorized access.
You also want to be able to get to your estate plan easily. You should review it at least once a year or whenever changes occur in your life or your family that may warrant a change to your plan. You may be adding things to it as well. For example, if you buy a new home or car and place it in your living trust, you'll want to include the appropriate documents with your other estate plan documents (and make sure your attorney has a copy).
Your estate planning attorney will tell you what their document storage procedures are and provide suggestions for the best way to keep your copies safe, yet accessible to the right people when the time comes.